Dryer with drum grounding mechanism

ABSTRACT

An electrical grounding device for use in connection with laundry appliances having an open-ended rotating drum. The grounding device consists of a metal member affixed to an electrical contact with the metal appliance body or cabinet adjacent the door opening and having an arm spring-biased toward the drum with a contact point on the end thereof adapted to contact a metal portion of the drum for grounding through the arm from the drum to the housing. An offset portion of the arm is provided with an abutment member which will be contacted by the door of the appliance, when closed, to lift the arm off of contact with the drum. When the door is open, the abutment member will be released and the spring bias of the arm will create mechanical and electrical contact with the drum.

United States Patent Zena [ 1 Feb.22, 1972 [54] DRYER WITH DRUM GROUNDING MECHANISM [72] lnventor: Fred J. Zenz, Berrien Springs, Mich.

[73] Assignee: Whirlpool Corporation, Benton Harbor,

Mich.

[22] Filed: Oct. 9, 1970 21] Appl. No.: 79,402

Primary ExaminerCarroll B. Dority, Jr. Attorney-James S. Nettleton, Thomas E. Turcotte, Donald W. Thomas, Gene A. Heth, Franklin C. Harter. Anthony Niewyk, Robert L. Judd and Hill, Sherman, Meroni, Gross & Simpson [57] ABSTRACT An electrical grounding device for use in connection with laundry appliances having an open-ended rotating drum. The grounding device consists of a metal member affixcd to an electrical contact with the metal appliance body or cabinet adjacent the door opening and having an arm spring-biased toward the drum with a contact point on the end thereof adapted to contact a metal portion of the drum for grounding through the arm from the drum to the housing. An offset portion of the arm is provided with an abutment member which will be contacted by the door of the appliance, when closed, to lift the arm off of contact with the drum. When the door is open, the abutment member will be released and the spring bias of the arm will create mechanical and electrical contact with the drum.

6 Claims, 3 Drawing Figures BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates generally to laundry equipment and more specifically to a grounding device for an open-ended laundry appliance drum.

2. Prior Art US. Pat. No. 3,284,918 is typical of many prior art clothes dryers wherein the tumbling drum is mechanically and electrically connected to the cabinet structure. Accordingly, drums of this type clothes dryer are electrically grounded and do not present the problem solved by the present invention.

US. Pat. No. 3,409,997, on the other hand, discloses an open-ended drum in a clothes dryer wherein the drum is suspended within the cabinet in electrical isolation from the cabinet structure. Such condition arises out of the fact that the front of the drum rides on an insulating bearing while the rear of the drum is sealed from a stationary bulkhead by a seal which is electrically insulating.

Permanent electrical connections such as slip rings or rotary contacts are subject to wear and entail additional expense as well as being potential sources of noise.

Accordingly, if an electrical potential is built up through tumbling of materials in the drum, or inadvertent contact of the drum with a bare wire the operator may receive a shock upon removing the materials from the drum.

SUMMARY OF THE INVENTION This invention overcomes the problems of the prior art and provides an electrical grounding contact between the drum and cabinet which is actuated whenever the cabinet door is opened to gain access to the drum. Inasmuch as the drum is normally stopped when the door is opened, the wear and noise problems which would otherwise be encountered with constant contacting grounds are avoided.

In a preferred illustrated embodiment, the ground consists of a strip of bent spring metal which is mounted in grounded contact to the cabinet adjacent the door opening. The strip has a long metal contact arm on one side of the attachment point and a short arm on the other side. The short arm terminates in an abutment member which projects through an opening in the cabinet wall into a door closure space where it will be abutted by the closed door to push it in the direction of the interior of the cabinet. Because of the spring nature of the strip, it will be biased toward the door so that when the door is open the abutment member will project further through the opening. The long arm moves with the short arm so that its movement is controlled by and is the reverse of the short arm. When the door is open, the long arm will project into the interior of the cabinet a sufficient distance to ground against an adjoining wall of the drum such as the radial wall and when the door is closed the long arm will be pivoted away from the drum.

Inasmuch as contact is created only when the door is open, the device may also function as a drum stopping brake, or may be appropriately modified to provide a mechanical braking action to quickly stop the drum when the access door is opened.

Many other features, advantages and additional objects of the present invention will become manifest to those versed in the art upon making reference to the detailed description which follows and the accompanying drawings, in which a preferred structural embodiment incorporating the principles of the present invention are shown by way of illustrative example only.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a fragmentary cross-sectional view of a laundry appliance equipped with the grounding device of this invention illustrating the appliance in its door-opened grounded state in full lines and in a door-closed dotted line position;

FIG. 2 is a fragmentary partially cross-sectional view of the laundry appliance of FIG. l in its door-closed ungrounded LII state and showing additional details of the dryer construction; and

FIG. 3 is a fragmentary cross-sectional view of the support for and rear end of the drum of the appliance of FIGS. l and 2.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Although this invention is of general utility, it has particular usefulness in connection with laundry appliances of the rotating open-ended drum type as illustrated and disclosed herewith.

FIG. 11 illustrates a laundry appliance such as a revolving drum front loading dryer. The appliance 10 consists of a housing or cabinet 11 in which is received a substantially cylindrical revolving open-ended drum 1 2 of the type disclosed in US. Pat. No. 3,409,447. A radial front wall B3 of drum 12 has an aperture 14 therethrough and the front 15 of the cabinet Ill has a substantially centrally disposed stepped flange opening 116 therein. The stepped flange 17 provides a circumferential ledge 18 recessed a slight distance into the cabinet ill. The flange 17 projects into the cabinet 11 to define an opening therethrough. The flange 17 is concentric with the peripheral wall 19 of the opening 14! and the front 113 of the drum l2 and projects therethrough. Preferably the flange l7 tenninates in an outwardly and backwardly directed portion 20 which terminates in relatively close spaced relation to the inner surface 21 of the peripheral wall 19.

Hinge-mounted to the cabinet 11 is a door 22 which has an inside 23 configuration adapted to fit in the stepped flange opening 116. Thus, the door 22 has a rectangular or other dimension portion 25 adapted to seat in the recess against the stepped wall 18 flush with the front of the cabinet and a boss portion 26 adapted to project into the opening defined by the flange 17. With the door closed, the inside face 23 contacts the wall 18 of the opening. A latch or spring mechanism not shown may be provided to maintain the door closed.

In the dryer embodiment illustrated, the drum I2 does not have a rear wall and at its end 30 remote from the door 22. Instead, as best illustrated in FIGS. 2 and 3, the end 30 terminates in spaced relation from a stationary wall 32 firmly attached to the cabinet. The space between the rear 30 of the drum and the wall 32 may be filled by a gasket 33 to prevent clothes within the drum from becoming entrapped in the space between it and the backwall. Preferably the gasket or sea] 33 is formed of an electrically insulative material susceptible to reducing friction and minimizing wear and therefore may not serve as an effective ground of the drum to the wall. A plurality of rollers 34 made of electrically insulative plastic material are attached to wall mounted axle members 35 and roll in circumferential grooves 36 and 36a indented into the peripheral wall of the drum. The grooves 36 and 36a may be spaced a short distance axially inwardly from the back and front of the drum respectively to support it adjacent the ends thereof. A motor 37 rotatably drives the drum via a belt 38 extending around the outer periphery of the drum.

Because of the insulator nature of the rollers 34 and the other nonconductive parts, the drum is mounted in the cabinet in electrical isolation with respect thereto.

In accordance with this invention there is provided a grounding member 50 which is automatically actuated into operative position by opening the door 22.

As illustrated in FIGS. l and 2, the grounding member 50 consists of a strap 51 of bent spring metal. A major portion 52 forms a body from which projects a bent leg portion 53. The leg portion 53 terminates in an out-tumed flange 54 which is attached to the front wall 15 of the cabinet 111 as by a rivet 55 or the like. With the flange 54 attached to the front wall, the leg portion 53 projects into the interior of the cabinet Ill where it terminates at a right'angle bend 57.

The body 52 is divided by the connection with the leg 53 into a long arm 58 and a short arm 59 disposed on opposite sides of the mounting leg 53. In this manner the attachment of the mounting leg 53 to the body 52 serves. as a fulcrum joining the short arm 59 and the long arm 58. By constructing the grounding member 50 out of electrically conductive spring metal, the long arm 58 will be biased toward the front wall 13 of the drum 12. At the same time the short arm 59 will be biased toward the front wall 15 of the cabinet 11. Preferably the mounting leg 53 is attached adjacent the opening 16 in the cabinet with the short arm 59 overlying the shoulder portion 18. An aperture 60 is provided through the shoulder 18 underlying the end of the short arm 59. An abutment member 61 is attached to the short arm 59 at a point adjacent its free end and is adapted to project through the opening 60 exteriorly of the cabinet. A stop ring 62 may be provided on the abutment member 61 to limit its forward travel through the opening 60.

By biasing the spring such that the long arm 58 normally is urged against the drum l2, electrical contact will be made between the drum and the cabinet via the member 50.

When the door 22 is closed, the inside face 23 will contact the abutment member 61 and move it toward the interior of the cabinet. The fulcrumlike attachment of the support leg 53 to the main portion 52 will cause the inward movement of the short arm 59 to act as an outward movement of the long arm 58 to lift it off of contact with the drum 12 as illustrated in FIG. 2. Therefore, when the door is closed, there will be no sliding contact between the drum and grounding member thereby reducing frictional drag, wear and noise.

To enhance the electrical contact when the door is open, the free end 60 of the long arm 58 will be arcuately bent inwardly to form a U-shaped portion 65 whose bight 66 contacts the drum 12. A cooperating arcuate groove 67 in the front wall of the drum will increase area contact between the long arm 58 and the drum.

Preferably the grounding member 50 of the illustrated embodiment is constructed of a single piece of resilient material such as spring steel and is bent so that the contact between the long arm 58 and the drum 12, when the door is open, is with sufficient force to create a good electrical contact. Thus, opening the door of the appliance will immediately ground the drum to the cabinet which in turn is grounded to an external ground not shown in accordance with conventional practice.

It will further be appreciated that the arm may act as a brake to reduce the rotational speed of the drum. Thus, if it is desired to exploit the grounding arm as a brake, the arm may be selected to exert sufficient spring force so as to provide a mechanical braking force thereby quickly stopping the drum when the access door is opened.

Although various modifications may be suggested by those versed in the art, it should be understood that I wish to embody within the scope of the patent warranted hereon all such modifications as reasonably and properly come within the scope of my contribution to the art.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. In a laundry appliance having a cabinet with a revolving drum insulatingly supported therein in electrical isolation and an access door through the cabinet to the drum, the improvement of a door actuated electrical grounding member including means effective to ground the drum to the cabinet in response to opening of the door.

2. In a laundry appliance as defined in claim 1 wherein the grounding member comprises a spring member attached to an interior portion of the cabinet and having a portion thereof spring-biased against a wall portion of the drum and means effective to prevent contact between a portion of the drum when the door is closed.

3. In a laundry appliance as defined in claim 2 wherein the said last mentioned means comprises a portion of the member adapted to be contacted by a portion of the door when it is closed to prevent contact of the biased portion with the drum.

4. A laundry appliance comprising a cabinet adapted to be electrically grounded, a revolving drum suspended in electrical insulation in said cabinet, an access opening through the cabinet to the interior of the drum, a door attached to said cabinet for selectively opening and closing said openin an electrical grounding member interior of said cabinet, an actuating means between said door and said grounding member operable to place said grounding member in grounding contact with said drum wherever said door is opened.

5. A laundry appliance as defined in claim 4 and further characterized by said grounding member having an arm portion spring-biased into contact with the drum and a second arm member spring-biased away from the said drum, the said first member and the said second member attached to one another through a pivot whereby movement of the said second member toward the said drum moves the said first member away from the said drum and said actuating means comprising means on said second member adapted to be contacted by the said door when closed to urge the said second member toward the said drum.

6. A laundry appliance as defined in claim 5 and further characterized by said ground member comprising a single piece of bent spring metal and said actuating means comprises an abutment member on the said second arm projecting through an opening in the said cabinet to a point where it will be contacted by the closing door. 

1. In a laundry appliance having a cabinet with a revolving drum insulatingly supported therein in electrical isolation and an access door through the cabinet to the drum, the improvement of a door actuated electrical grounding member including means effective to ground the drum to the cabinet in response to opening of the door.
 2. In a laundry appliance as defined in claim 1 wherein the grounding member comprises a spring member attached to an interior portion of the cabinet and having a portion thereof spring-biased against a wall portion of the drum and means effective to prevent contact between a portion of the drum when the door is closed.
 3. In a laundry appliance as defined in claim 2 wherein the said last mentioned means comprises a portion of the member adapted to be contacted by a portion of the door when it is closed to prevent contact of the biased portion with the drum.
 4. A laundry appliance comprising a cabinet adapted to be electrically grounded, a revolving drum suspended in electrical insulation in said cabinet, an access opening through the cabinet to the interior of the drum, a door attached to said cabinet for selectively opening and closing said opening, an electrical grounding member interior of said cabinet, and actuating means between said door and said grounding member operable to place said grounding member in grounding contact with said drum wherever said door is opened.
 5. A laundry appliance as defined in claim 4 and further characterized by said grounding member having an arm portion spring-biased into contact with the drum and a second arm member spring-biased away from the said drum, the said first member and the said second member attached to one another through a pivot whereby movement of the said second member toward the said drum moves the said first member away from the said drum and said actuating means comprising means on said second member adapted to be contacted by the said door when closed to urge the said second member toward the said drum.
 6. A laundry appliance as defined in claim 5 and further characterized by said ground member comprising a single piece of bent spring metal and said actuating means comprises an abutment member on the said second arm projecting through an opening in the said cabinet to a point where it will be contacted by the closing door. 